Which movie(s) do you think has the best soundtrack?
I think American Psycho has a good soundtrack and I listen to it occasionaly.
More general answer than you expected, but…
I really like when the sound design in movies makes sense - it “plays” in radio, gramophone…
For example “Black hole sun” cover in first episode of Westworld is just brilliant and caught me off guard (I didn’t know what it is about).
The adjective for this type of music is “diegetic”. That’s sound which is occurring and audible in-universe, not just to the audience.
My favourite example of this is in Grosse Point Blank, when the GNR cover of Live and Let Die is playing non-diagetically, right until the moment Martin walks into the store, and suddenly a cheesy muzak version of it is playing over the shop radio. It’s beautifully done :-)
Haven’t watched it yet, but I love Black Hole Sun. I’ll definately check it out